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Compounds of pentachlorophenol and particularly the sodium salt (Na-PCP), have been widely used for a variety of agricultural and industrial purposes. The pollution of aquatic ecosystems by Na-PCP has assumed serious proportions due to its toxicity and accumulative effect in organisms and environment. The objective of this laboratory study was to examine and quantify the histopathological effects of Na-PCP on the structure of the gill, as one of the most important organs targeted by phenol entries, in the freshwater snail, Holandriana holandrii. Based on the results of a preliminary mortality test, three experimental concentrations were chosen: 0.56, 1.00 and 5.6 mg L-1 Na-PCP for the semi-static test. Histological sections, stained with hematoxylin and eosin, were observed under a light microscope equipped with digital camera and analysed with image analysis software to quantify histopathological lesions. Results indicated serious structural changes in epithelial cells and underlaying connective tissue of gills, which were accelerated with an increase of Na-PCP concentrations and more pronounced in relation to the exposed period. Significant gill structural changes appeared as a progressive necrosis at epithelial cells and the epithelial lining was interrupted, while connective tissue exhibited vacuolization, formation of large irregular spaces and damaged chitinous rods. Epithelial height measured showed significant difference among experimental groups exposed to different concentrations of Na-PCP and control. Further on, measured connective tissue width also showed a statistically significant difference. We can conclude that the histomorphometric approach in quantifying of toxicant effects on animal tissue could be applied in legislative prevention of adverse effects in freshwater ecosystems, and H. holandrii can serve as a good indicator of freshwater deterioration.

Individuals of symbiotic green hydra (Hydra viridissima Pallas, 1766) and free-living brown hydra (Hydra oligactis Pallas, 1766) were treated with aqueous solutions of herbicide norflurazon (2x10-7, 2x10-6 mol/L) for 72 h and hydras were also exposed to simultaneous treatment to norflurazon and UVB radiation (λ = 254 nm, 2 min), along with control groups. The experiment was performed in triplicate. Migration and change of body shape (relaxed, contracted), as the evasion signs of deleterious effects, were observed by stereo microscope, and responses to mechanical stimuli were also noted. Comet assay was applied to measure the level of primary DNA damage of exposed green and brown hydras. Beside single and double strand breaks, it detects DNA base alkylation, oxidatively changed bases, DNA-adducts, covalently bound proteins to DNA, cross-linking and base dimers. Each hydra was put into a conical tube containing chilled homogenization buffer (75 mM NaCl, 24 mM Na2EDTA, pH 7.5, +4 °C) and its cells were separated mechanically. The obtained homogenate was mixed with the low melting point agarose, spread across the microscopic slide and left for the gel to polymerize. Preparations were treated with a series of buffers to remove the cell structures and isolate nucleoids. By immersing the slides into alkaline buffer, pH 13.0, DNA denatures rapidly. At the spots of primary damage, DNA strands broke, which led to the formation of relaxed loops and free DNA fragments. In electrophoresis, these loops and fragments are pulled from the nucleoid core toward the anode, and following fluorescent staining, under the microscope, they appear as comets. Comet preparations were analysed under an epifluorescent microscope equipped with CCD camera, and the level of damage was measured by image analysis software for the comet assay. Based on the intensity of fluorescence of the tail compared to the nucleoid, the percentage of DNA affected by primary damage was calculated. The treatment did induce a concentration related increase in primary DNA damage, but no significant difference between green and brown hydra was observed (4.40 % vs. 5.23 %, respectively ; negative controls 1.13 % and 1.17 %, respectively). On the other hand, in the presence of radiation, brown hydras showed significantly higher level of primary DNA damage already when exposed to the lowest concentration compared to the green ones (15.10 % and 3.77 %, respectively), proving the advantage of the symbiotic organism. The increase in damage was concentration dependent in either case.

The pollution of aquatic ecosystems by sodium pentachlorophenolate (Na-PCP) has assumed serious proportions due to their toxicity and accumulative effect in organisms and environment. The objective of this experimental study was to examine and quantify the histopatological effects of Na-PCP on the structure of hepatopancreas and gill, as two most important organs targeted by phenol entries, in the freshwater snail, Holandriana holandrii. Results indicate serious structural changes in tissue and epithelial cells of both organs and were accelerated with increase of Na-PCP concentrations and more pronounced related to exposed period. In hepatopancreas, tubular lumen, vacuole surface and number per tubule, exudate area in the tubular lumen, all increased with increase in concentration. Opposite trend of decreased height was observed for digestive and basophil cells. Significant gill structural changes appeared as a progressive necrosis at epithelial cells and the epithelial lining was interrupted, while connective tissue exhibited vacuolization, formation of large irregular spaces and damaged chitinous rods. Histomorphometrical approach in quantification of toxicant effects on the organism tissue could be used in legislative prevention of hazardous effects in freshwater ecosystems and H. holandrii may serve as a reliable and sentinel indicator of freshwater deterioration.

Proizvodni program brodogradilišta usmjeren je na putničke brodove duljine do 150m. Dimenzije i forma brodova su takve da se u strukturi nalazi veći broj zakrivljenih sekcija, pa je potrebno analizirati metode predmontaže. Članak najprije prikazuje pregled broja, masa i geometrijskih karakteristika zakrivljenih sekcija karakterističnog broda iz proizvodnog programa brodogradilišta. Za karakteristične zakrivljene sekcije prikazane su metode sastavljanja koje se koriste u proizvodnom procesu. Definirane su aktivnosti metoda, faze sastavljanja, prednosti i nedostaci postojećih metoda izrade zakrivljenih sekcija. U članku je prikazan prijedlog efikasnije metode sastavljanja zakrivljenih sekcija sa definiranim aktivnostima i fazama sastavljanja što uključuje raspored radnih površina i tokove materijala. Aktivnosti metoda su uspoređene, a zaključno su navedene prednosti korištenja predložene metode sastavljanja zakrivljenih sekcija.

Rotifers and planktonic crustaceans (cladocerans and copepods) occupy a central role in the food webs of shallow water bodies, connecting autotrophic (algae) with heterotrophic mode in the food webs. Differences between temperate-continental and Mediterranean climates affect variously interactions of abiotic and biotic factors. The aim of this study was to determine: (i) the diversity, abundance and trophic structure of zooplankton ; (ii) zooplankton indices in comparison to the trophy state indices ; (iii) a proposal for measures in the management and conservation of shallow water bodies in two different climates. In nine ponds, 48 species of zooplankton were determined, and rotifers dominated with 36 species. Habitat complexity, macrophyte coverage, and nutrient concentrations were indicated as significant factors in the structuring of zooplankton in shallow water bodies of both climate regions. Zooplankton in the temperate-continental climate was characterized by populations of higher diversity, while in the Mediterranean climate zooplankton was characterized by populations of lower diversity and higher abundance, particularly species of genera Lecane and Brachionus. Results of this study support the importance of zooplankton as a sentinel indicator in assessing the trophic and ecological status of shallow water bodies and provide a basis for determining guidelines in the conservation and management of these sensitive and endangered ecosystems.

Iako je Bosna i Hercegovina postigla značajan napredak na svim područjima u poslijeratnom razdoblju, ona se još bliži statusu kontinuirane opće krize i izložena je velikom riziku pogoršanja situacije pod utjecajem globalne financijske, ekonomske i socijalne krize. Nekoliko je uzroka opće krize: ekonomska situacija, socijalni položaj stanovništva, politička ne- stabilnost i onemugućavanje vladavine prava, koji će ugrozit integraciju Bosne i Hercegovine u Europsku uniju. Pitanja su o kojima ćemo govoriti u ovom radu: Imamo li vladavinu zakona u Bosni i Hercegovini Da li je moguće procesuirati i otpuštati politički neodgovorne ljude Da li je moguće spriječiti različite oblike viktimizacije građana Bosne i Hercegovine zbog različitih oblika zlouporabe vlasti u Bosni i Hercegovini Imamo li "demokracija" u krizi u Bosni i Hercegovini Da li smo žrtve zlouporabe položaja

Symbiotic green hydra (Hydra viridissima Pallas, 1766) and non-symbiotic brown hydra (Hydra oligactis Pallas, 1766) were exposed to the UVB-radiation and/or herbicide norfluorazon in order to determine their effect on extracellular layer mesoglea. The experiment was performed using crystallizing dishes 60 ml volume with either 50 ml of aquarium water or with two norflurazon solutions (2x10-6 and 2x10- 7 mol/L). Ten individuals of green and brown hydra respectively were placed in separate dishes and five individuals of each species were placed together in a dish. All specimens were exposed to UVBrays with a wavelength of 254 nm for two minutes. The second part of the experiment was performed in the same way except there was no UVB-radiation. Hydras placed in aquarium water were not exposed to the UVB-radiation, as a control group. The experiment was performed in triplicate for 72 hours and hydras were monitored every 24 hours. For slide preparation, standard histological methods were used and slides were stained with hematoxylin and eosin. ImageJ software was used for the morphometric measurements. Thickness of mesoglea was measured at 30 randomly selected segments on the histological slides, per particular treatment. Mesoglea was least thick in the samples of green and brown hydra exposed to UVB-radiation, while the greatest thickness was noted in the group of both species treated with norflurazon concentration of 2x10-7 mol/L. The results indicated that xenobiotics could have an impact on alteration of mesoglea thickness in hydra, which can affect physiological and regenerative processes in symbiotic and non-symbiotic hydras.

Ecotoxicological observations of cytological measurements were performed on the freshwater planarian Polycelis felina (Dalyell, 1814) and cnidarian Hydra viridissima (Pallas, 1766) with the aim to determine morphometrical changes of their cell structures. P. felina was exposed to aluminium (80 and 100 mgL-1 for 48 h). H. viridissima was exposed to cinoxacin (1.9x10-3 and 3.8x10-3 mol/L for 72h) and chloramphenicol (2x10-4 mol/L for 24h and 3x10-4 mol/L for 24 and 48h). Both species were exposed to herbicide norflurazon (2x10-6 mol/L) for 3, 24 and 48h. In hydras morphometrical changes were observed in number and area of zymogen and interstitial cells, area of ectoderm and gastroderm, mesoglea thickness, size of ectodermal myoepithelial cells and diameter and area of endosymbiotic algae. In planarians morphometrical changes were observed in the size and number of neoblasts and in the size of the reticular cells, rhabdites and rhabdite layer. The results of morphometric analysis showed changed structures of different cell types, significantly correlating with an increase of toxicant concentration and longer exposure, compared with the control samples. Morphometry proved to be a powerful tool in research of ecotoxicological impact of xenobiotics upon freshwater organisms.

Turbellarians (flatworms, Platyhelminthes) in freshwater or moist terrestrial environments are mainly predatory species. In these experimental setups, we assessed interaction between turbellarians Dugesia gonocephala (Duges, 1830) and Polycelis felina (Dalyell, 1814) in terms of their competitive capability. In ex situ microcosms experiment turbellarians were exposed through the day-night rhythm to different temperature and light conditions: 25 °C and 8 h light, 13.5 °C and 16 h dark, respectively. The results were recorded immediately and every 1, 8 and 24 h after the beginning of the experiment. Five replicas with both fed and starved animals were set up. Species D. gonocephala, in both conditions of temperature and light, attacked and preyed upon P. felina and took over pigmentation from P. felina considering that P. felina is black colored and D. gonocephala is grey transparent. There was no reverse process recorded. Moreover, it was noticed that previously fed D. gonocephala specimens more likely attacked P. felina than starved individuals did. Also, the higher rate of predation was present at higher temperature (25 °C) than under the conditions of lower temperature (13.5 °C). Generally, when turbellarians were put in microcosm at the beginning of the experiment, they were very agile searching for prey. Afterwards, D. gonocephala and P. felina rested mostly on the opposite sides of microcosms. Results of our study indicated new insights into predation among turbellarians and more information about freshwater micro-ecosystem food competition.

The goal of this research was to study interactions among carnivorous invertebrates: green hydra (Hydra viridissima Pallas, 1766), and turbellarians Dugesia gonocephala (Duges, 1830) and Polycelis felina (Dalyell, 1814). In ex situ microcosms experiment animals were exposed through the day-night rythm (8 h light/16 h dark) and different light and temperature (25 °C/13.5 °C) conditions, both separately with starved and fed animals. The results were recorded immediately after the experiment setup and every 1, 8 and 24 hs after the beginning of the experiment, including the controls. Experiment was set up with 1 and 5 animals of each species, 5 replicas for each setup. In the view of interference competition, behaviour indicated habitat separation: fed D. gonocephala was resting on the side and hydra on the bottom of microcosm, with partial migrations in water column. Starved D. gonocephala were agile and hydra was on the bottom of microcosm, with no migrations present. In microcosm with fed P. felina, hydra was budding and P. felina were mainly resting. Starved specimens of P. felina were active and hydras were relaxed. Interspecies predation occurred between D. gonocephala as a predator and P. felina as a prey, mainly observed with starved animals. P. felina used aggregation as the mechanism of protection. Results of this study suggested hydra as better-equipped predator, probably due to cnidocytes, than turbellarians. Two or more predatory groups can coexist, however closely related interspecies predation could appear.

Quercetin is the most significant flavonoid which is an antioxidant, but sometimes it also performs a prooxidative effect. Brown hydra (Hydra oligactis Pallas, 1766) is a freshwater animal belonging to the phylum Cnidaria. It was treated with quercetin (0, 2, 0, 25, 0, 3 gL−1) and compared to the control, as well as endosymbiotic algae isolated from green hydra Desmodesmus subspicatus (Chlorophyceae) (Chodat) Hegewald and Schmidt, Mychonastes homosphaera (Chlorophyceae) (Skuja) Kalina and Punčochářová and free-living related alga Chlorella vulgaris Beij. [K&H, 1992], strain SAG 211-11b. Morphological changes were observed by using a stereo microscope and included migration in the experimental dish, reactions to mechanical stimuli, secretion of mucus from hydra body and mortality. Cytological and histological changes were observed using light microscopy. At higher concentrations of toxicant quercetin caused damages of ectoderm and gastroderm of brown hydra and growth inhibition of endosymbiotic algae. Free-living alga treated with quercetin showed higher viability compared to the isolated endosymbiotic algae.

Flavonoids are plant pigments found in fruit, vegetables, tea, flowers and wine. Naringenin is a flavonoid that belongs to the group of flavanones and its effect was monitored on hyda – alga symbiosis. As test organisms used were: Hydra viridissima Pallas, 1766 and Hydra oligactis Pallas, 1766, endosymbiotic algae isolated from the hydra host Mychonastes homosphaera (Skuja) Kalina and Punčochářová, Desmodesmus subspicatus (Chodat) Hegewald and Schmidt and related free – living species Chlorella vulgaris Beij. Morphological and cyto – hystological analysis was made using concentrations of 0, 2 gL−1, 0, 25gL−1 and 0, 3 gL−1 of naringenin. It was determined that the middle concentration does not favor growth of the organisms. Mortality, budding, mucus secretion, migration and contractions of hydra as well as viability of algal cells were monitored by stereo microscopy and changes in structural cell organization were observed by light microscopy.

Zelena hidra (Hydra viridissima Pallas, 1766) i smeđa hidra (Hydra oligactis Pallas, 1766) ili obje vrste zajedno izlagane su herbicidu norflurazonu koncentracija 2x10-7 i 2x10-6 mol/L. Dio hidri izložen je sinergističkom djelovanju norflurazona i UVB-zračenja valne duljine 254 nm tijekom 2 minute. Hidrama su dodane monokulture slobodnoživuće alge Chlorella vulgaris (CV) i endosimbiotske alge Mychonastes homosphaera (CZ10) ili suspenzija obje vrste zajedno. Pokus je u istim uvjetima izveden i bez dodatka algi. Praćeno je nespolno razmnožavanje (pupanje) hidri tijekom tri dana. U hidra s dodatkom algi nespolno razmnožavanje je bilo puno jače izraženo. Smeđa hidra je pupala u većem postotku od zelene hidre, izložena različitim tretmanima. Nespolno razmnožavanje je bio najveće trećeg dana, kada je pupalo i do 100% jedinki smeđe hidre. Bez dodatka algi hidre su se nespolno razmnožavale u puno manjem postotku. Time je ukazana uloga algi kao potencijalnih pojačivača/promotora nespolnog razmnožavanja hidri u akvakulturi. Green hydra (Hydra viridissima Pallas, 1766) and brown hydra (Hydra oligactis Pallas, 1766), either separately or both species together were treated with 2x10-7 and 2x10-6 mol/L of aqueous solution of herbicide norflurazon. Hydras were also exposed to synergistic treatment with norflurazon and UVB-radiation (λ=254 nm, 2 min). Monocultures of free-living alga Chlorella vulgaris (CV) and endosymbiotic alga Mychonastes homosphaera (CZ10) were added to the experimental dishes, either separatately or suspension of both species together. The experiment was also performed in the same experimental conditions without algal suspensions. Asexual reproduction (budding) of hydras was monitored for three days. In the samples with the addition of algae budding was extremely expressed. Brown hydra reproduced asexually more often when compared with green hydra, in different tested conditions. The largest percentage of asexual reproduction was present on the third day with up to 100% in brown hydras. Hydras without algal suspensions asexually reproduced in a much lower percentage. Algae proved to be potential promotors/enhancers of asexual reproduction of hydras in aquaculture.

Hydra (Cnidaria) is a cosmopolite freshwater invertebrate that establishes symbiosis with unicellular algae. Its simple body is comprised of three layers: epidermis, mesoglea and gastrodermis. The goal of this research was to determine the effect of flavonoids quercetin and naringenin upon hydra – alga symbiosis, to determine how motivated teachers are to perform such a mode of teaching and whether this motivation depends on their age, years of working experience, the school they work in, available time, space and material. An anonymous survey on a sample of 100 biology teachers was used in the research. Hydras and algae were treated with quercetin and naringenin in concentrations of 0.2, 0.25 and 0.3 gL−1 and compared to the control, and Chlorella bioassay was used. Morphological changes included migration, reaction to mechanical stimuli, asexual reproduction, secretion of mucus and mortality. Cyto- histological analysis revealed changes of all three layers and growth inhibition. Naringenin exerted altogether higher impact than quercetin. Survey results indicated that teachers are willing to use this experiment in school, and that most schools have the minimum required equipment. Because of the possibility of adapting this experiment in different temporal and spatial conditions, its performance in school is suggested.

After 14 years, the Multinational Congress on Microscopy again took place in Croatia, this time in Rovinj, on September 24–29, 2017. MCM 2017 was jointly organized by the Croatian Microscopy Society, with the Ruđer Bošković Institute, Zagreb. MCM 2017 brought together leading experts and young researchers who develop microscopy methods and apply them in the fields of life and material sciences. Altogether, more than 450 delegates from 30 countries participated with a keynote and seven plenary lectures, 42 invited talks and 84 short talks in 3 parallel sections and 175 posters.